High pressure, high temperature pump



Dec. 16, 1958 J. T. CULLETON HIGH PRESSURE, HIGH TEMPERATURE PUMP Filed May 11, 1955 INVENIOR. JOHN r CULLETON BY ATTORNEY.

densate, such parts being the :traps,

2,864,314 HIGH PRESSURE, HlGH TEMPERATURE PUMP John T. Cnlleton, Hayward, Calif assignor to Pacific Pumping Company, Qalrland, Calif., a corporation of California Application May 11, 1955, Serial No. 507,601 2 Claims. (Cl. 103-96) This invention relates to improvements in fluid pumps and particularly to pumps adapted for pumping liquids at high temperature and under high pressure.

The pumping of liquids when close to their flash point, such as in the condensate return system in a steam heating plant for drying plywood, has proved particularly troublesome because in such a case the optimum condition is to return the condensate to the boiler with the minimum possible heat loss. The rotating pump shaft must be sealed against loss of fluid and pressure along the shaft. The heat generated by the shaft seal is often enough to raise the temperature of the liquid back to its flash point, thereby robbing the shaft seal of the lubricating effect the fluid has when in liquid form.

It is therefore an object of the present invention to provide a pump construction which will assure the retention of the fluid in liquid form in the housing adjacent the bearings and yet will leave the fluid in the pumping zone of the pump housing at an elevated temperature on one side or the other of its flash point.

Another object of the invention is to effect heatsavings in lower fuel costs and less maintenance on the boiler because by maintaining the fluid condensate in the pumping zone at as high a temperature as possible there is less work for the boiler to do in lifting this condensate to its vapor phase. a 1

Another object of the invention is to reduce the amount of make-up water needed in operating a boiler, thereby saving in water treatment costs.

Another object of the invention is to eliminate the extra parts usually needed in the fluid system where there is a substantial drop in temperature of the convalves and fittings. I

Another object of the invention is to reduce the back pressure on the device in which the steam is being used,

following description of a preferred embodiment of the invention, given to explain its principle and functioning so that those skilled in the art may practice it'upon the expiration of this patent. In thus complying with the statute, it is not the inventors intention to limit the invention to this one form, as its principles may be practiced in other forms.

The single figure of the drawings is'a cross-sectional view in elevation of a fluid pump in which is incorporated the structure of the invention- The invention is especially adaptable to use in. any

pump where the fluid being pumped is at an elevated temperature close to its flash point and where it is desirable, for reasons already stated, that this temperature should be maintained in the pumping chamber, but where the circulation of the fluid at that temperature near the steamers, checks,

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pump shaft seal will cause it to flash into its vapor phase and thereby deprive the pump of the lubricating effect the fluid has while in its liquid phase. The alternative heretofore has been to cool the fluid being pumped so that the friction of the pump shaft seal would not generate enough heat to raise the fluid to its flash point.

For purposes of illustration I have shown a twin impeller pump of a well-known type, which I have altered in the areas on each side of the pump housing proper where my invention is placed. To shorten this description only one half of the device in the drawing will be referred to in detail as it is a duplicate of the other half.

The pumping zone proper may be any satisfactory construction having provision for entry of the fluid (not shown) and an outlet 10 connected to the line leading back to the boiler (not shown). The pump end housings 11 are suitably secured to the central housing member 12, with O ring sealing members 13, 14 effecting a leak tight fit to form a pumping zone 15, inside of which are fitted the usual replaceable pump liners 16 in close proximity to the pump impellers 17. The latter are keyed to the pump shaft 18. Suitable passageways in the pump housing (not shown) conduct the fluid from the inlet to the outlet 10. Some of these are shown at 19, 20 and 21.

As stated, my invention is employed adjacent the pumping zone where it is desired to maintain some of the fluid being pumped at a lower temperature than the fluid in the pumping zone. This is accomplished by means of a partition 22 between the shaft seal 23 and the pumping zone 15, with the partition having sufficient openings or a clearance 24 to admit a small flow of fluid into the seal chamber 25, and having means for cooling the condensate that flows past it from the pumping zone 15 into the seal chamber 25. To'have room for the cooling partition or sleeve 22 in the end housing 11 of an existing pump, new end housings were made having an extended tubular member 26 to carry the shaft bearings 27, the shaft seals 23and the cooling partitions or sleeves 22. It also was necessary to make the shaft 18 longer.

Detail on the form of pump'used to describe my invention shows the end housing 11 having theradial'end wall 30, with the cylindrical tubular member 26. In-' side the latter is assembled the annular cooling sleeve 22, held in place by spring lock rings 31 and 32 with 0' rings 33 sealing the sleeve 22 against the bore wall 34. The cooling sleeve 22 is U-shaped in cross-section so that its open side forms, with the bore wall 34, an annular jacket 35 in which cooling water is circulated. It has a thinwall at 36 where the heat is to be drawn out of the condensate as it flows into the seal chamber 25. Suitable ports 37 and 38 are provided in the end housing 11 to get the cooling water into and out of the annular jacket 35. The inside diameter of the bore forin ing the annular wall 36 will be slightly larger than the diameter of the shaft 18 to form a gap or passageway 24 between the pumping zone 15 and the sealing chamber 25. The size of this gap will be determined by the tem perature drop desired between the fluid in the pumping zone and inthe sealing chamber, and thefrelative effec tiveness of the cooling chamber 35. In a pump used on a condensate returnline where thecooling water was introduced at 50 R, where the wall 36 was Ms" thick, and where the pump shaft 18 was A2" in diameter, I obtained satisfactory operating results with a ,4 clearance at 24 between the shaft and the wall 36.

At the outer end of the sleeve 26 and spaced from the annular cooling member 22 is the shaft bearing 27 and the shaft seal member 28. Both of the latter are shown mounted in a ring 40 having an annular recess 41 to receive the outer race of the bearing 2'7 and a recess 42 to receive the stationary sealing face 28 of the shaft seal. The ring 40 is held in by the lock rings 43 and 44 with an O ring 47 to seal the ring 40 in the sleeve 26. A bearing lubricating port is provided at 45. The movable portion- 23 of the shaft seal is secured on the shaft, 18 with a press-tight fit so the matched sealing face 46'bears against the stationary sealing face 28. It is the friction generated by these sealing faces which in the past has caused the condensate adjacent them to flash into a vapor phase thereby depriving them of the lubricating effect of the condensate when inits liquid plane.

I have discovered that by fencing off the sealing chamber from the pumping zone with only a small passageway for the condensate to go from one to the other, and by cooling the condensate that does flow into the sealing chamber, I can cool the small amount of condensate in the sealing chamber so it does not flash back to a vapor phase and I can preserve the condensate in the pumping zone at a temperature very close to its flash point so that, when it gets back to the boiler, very little heat is required to turn it into steam.

Sample temperatures taken on an experimental device showed that in the pumping zone the condensate under pressure was from 350 to 400 degrees F.; the condensate that passed along the passageway 24 into the sealing chamber 25 was from 85 to 90 degrees F.; and the cooling water circulating in the cooling jacket was. from to 70 degrees. The result was the life of the shaft seal was many times greater than ever before in this type device; the boiler had less work to do; and the pump was shut down for repairs very infrequently compared to earlier devices.

Thus this invention brings a new principle of operation into pumps for fluids, where the fluids are being pumped at temperatures close to their flash point. The concept of the organization is new and the results obtained solve a long standing problem in this art. Prior to this invention, the inventor and others in the art have tried with ,liquid cooled jackets to lower the temperature of the fluid at the shaft seals to add life to the seals, but these efforts have failed. They failed for several reasons, one being that in the case where condensate is being pumped back to the boiler, the heat generated by friction of the shaft seal parts is enough to flash the condensate from a liquid to a gaseous state. This deprived the seal parts of the necessary lubricating effect of the liquid and resulted in scored shafts and prematurely worn seal parts. On the other hand, when the cooling jacket around the shaft seals was made more effective to prevent the liquid from flashing to a vapor phase, the temperature of the condensate was lowered so much as to require the boiler to do extra work in heating it up. This cost extra fuel and time.

There are several ways the structure which produces the new principle of the present invention might be described. One would be to view it as means for dividing the pump into separate zones, so that the pumping area is in one zone and the shaft sealing device or devices is in its own sealingzone. These zones are separated by a liquid jacketed means extending in close to the shaft but spaced from it just far enough to permit some of the fluid being pumped to flow into the shaft seal zone. This has the practical effect, first, of cooling the condensate well below its flash point as it goes by the liquid jacketed cooling means into the sealing zone; second, of confining in the shaft sealing zone this cooled condensate so it does not mix particularly with or cool the condensate being handled in the pumping zone, and third, of assuring the presence of a liquid in the shaft sealing area to serve as alubricant.

One practical effect has been to lengthen the life of the shaft seals from 18 days to several months. Another practical effect has been to reduce the fuel bills for firing the boiler. One installation on which experimentaluse of the device was made effected a saving of about $1Q00 4 a month in fuel, primarily because the condensate was returned to the boiler at a temperature so high, it took very little heat to raise it to a vapor phase.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will sug gest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. A pump for hot fluids, including in combination a housing with inlet and outlet ports; a shaft mounted for rotation in said housing; a pump impeller mounted rigidly on said shaft; a face-type shaft-sealing assembly having a first face-seal member rotatably mounted on said shaft, 2. second stationary face-seal member mounted on said housing, and spring means urging a face of said first member into sealing contact with a face of said second member; and partition means between said impeller and said shaft-sealing assembly, forming part of said housing, dividing the interior of said housing into a pumping zone and a sealed chamber, and providing relatively narrow clearance around said shaft, suflicient to allow restricted entry of fluid from said pumping zone into said sealed chamber, said partition being provided with passage isolated from both said pumping zone and said chamber for circulating a coolant therethrough to cool the fluid passing through said clearance, whereby a cooled small fraction of the fluid being pumped iubricates the faces of said face-type shaft sealing member so as to protect them against wear during their relative rotation against each other with their sealing action, said cooling preventing vaporization of the fluid and resultant loss of its lubricity from the heat of friction caused by relative rotation of said seal faces against each other.

2. A pump for liquid close to its boiling point, and under high pressures, including in combination a housing with inlet and outlet ports leading into and from an interior; bearings secured in said housing; a shaft mounted for rotation on said bearings; a pump impeller mounted rigidly on said shaft; a face seal having a first member rotatably mounted on said shaft, a second member mounted stationary on said housing, and spring means urging a face of said first member into sealing contact with a face of said second member, said face seal separating the interior of said housing and the liquid therein from said bearings; and partition means between said impeller and said face-seal, forming part of said housing, dividing the interior of said housing into a pumping zone and a sealed chamber, and providing relatively narrow clearance around said shaft, sufficient to allow restricted entry of liquid from said pumping zone into said sealed chamber, said partition being provided with a passage isolated from the interior of said housing for circulating a coolant therethrough to cool the liquid passing through said clearance, whereby a cooled small fraction. of the liquid being pumped lubricates said faces of said faceseal so as to protect them against wear due to their rotating relatively while sealing against each other, the cooling of the liquid preventing vaporization of the liquid and resultant loss of its lubricity from the heat of friction caused by relative rotation of said seal faces against each other. 7

References Cited in the file of this patent UNITED STATES PATENTS 2,203,525 Dupree June 4, 1940 2,427.656 Blum Sept. 21, 1947 2.493.602 Sterrett Ian. 3, 1950 2,555,492 Kidney June 5, ll

FOREIGN PATENTS 114,725 Austria Oct. 25, 1929 651,299 Great Britain Mar. 14, 1951 

